The variation in gene pools between the 30 pupfish populations occurred through an evolutionary...?

6) A. Natural Selection is a the idea that is based on genetic variation in a species. When a specific organism in the species has a trait that is harmful, odds are they will die from it. Since they die, they can't reproduce and p on their genes, so the bad trait dies with them. It doesn't matter where the trait comes from, if it causes harm that results in death, the animals cant give the harmful allele to future generations.